1. Field of the Invention
The present invention relates to a variable inductance element having a predetermined inductance and used as either part of a semiconductor or other device, or as a discrete element.
2. Background Art
The rapid advancement of electronics technology in recent years has brought about the broad use of electronic circuits in a wide range of fields. In particular, progress in semiconductor manufacturing technology is continuing to make high integration LSI and other devices commonplace.
These type of integrated circuits comprise large numbers of semiconductor components, including NOS transistors, bipolar transistors, diodes and others. Other components, such as capacitors utilizing pn junctions and resistors with characteristics determined by the density of minority carrier in the semiconductor are also incorporated into the devices. Consequently, large scale integrated circuits (LSI) are constructed with nearly all of the individual components contained internally.
However, in the case of conventional integrated circuits, although nearly all the circuit elements could be included internally, coils had to be provided externally to the device. Also, since the inductance of a coil is determined by the coil shape, suitably changing the inductance according to requirements after fabrication was impossible. For example, a known means of variably setting the inductance is to insert a magnetic core. However, in order to change the inductance, the position of this magnetic core needs to be shifted. Therefore, manufacturing of such an inductor is complex, and use as a portion of an integrated circuit is impossible.